We have recently devised a scheme for raising C57BL/6 cytotoxic T cells to a weakly immunogenic, syngeneic tumor E male G2). This tumor was originally induced by AKR/Gross type murine leukemia virus (MuLV) and is the prototype cell for the definition of Gross cell-surface antigen (GCSA). Production of these cytotoxic T cells required both primary in vivo immunization with allogeneic, ion tumor cells (AKR SL3) and secondary in vitro restimulation of primed spleen cells with GCSA ion tumor cells of H-2b histocompatability type histocompatability type E male G2 or AKR.H-2b SLI). Cytotoxic T cells raised in this manner recognized only E male G2 and AKR.H-2b SLI, not AKR SL3 or syngeneic GCSA-, target cells. These data are thus consistent with the conclusion that the cytotoxic cells are H-2 restricted and directed against MuLV-associated antigens. We wish to test this hypothesis and extended our findings by investigating the following aspects of these cytotoxic T cells: 1) requirements for induction, 2) specificity and H-2 restriction, 3) genetic regulation of induction, and 4) immunotherapy. Our general approach to determine the requirments for induction and genetic regulation induction of cytotoxic T cells to syngeneic, GCSA ion tumors will be to vary either the form of antigenic stimulation or the strain of responder mice employed. The questions of the possible restricted nature and the specificity of these cytotoxic cells will be addressed by a variety of approaches including the use of high titer, monoclonal anti-viral antibody preparations from hybridoma cells to block recognition sites on target cells. In each of these three areas, the data to be analyzed will largely be obtained by 51 Cr-release microcytotoxicity assays. The potential immunotherapeutic value of these cytotoxic cells will be assessed by measuring their effect on the survival of C57BL/6 mice given the syngeneic tumor E male G2. It is hoped that these studies will provide guidelines which may have general applicability to the induction and immunotherapeutic use of cytotoxic cells to weakly immunogenic, syngeneic tumors.